Liquid-fuel burner



Dec. 16, 1930. E. F. WHITE 1,785,707

LIQUID FUEL BURNE Filed April 9, 1929 Patented Dec. 16, 1930 UNITED STATES PATENT OFFICE EZEKIEL F. WHITE, 0F HARTFORD, CONNECTICUT, ASSIGNOR TO GROVER V. LASSEN, 0F WEST HARTFORD, CONNECTICUT LIQUID-FUEL BURNER Application led April 9,

This invention relates to liquid fuel burners and more particularly to those of the centrifugal, atomizing type, where liquid fuel is delivered in atomized form under centrifugal force to the combustion chamber of the furnace by a high speed rotating fuel atomizing member.

The invention has for its object more especially'improvements designed to prevent intense heat, to which portions of the atomizer mav be exposed, from coling or carbonizing theufuel within theatomizer, from distorting the struct-ure of the atomizer, or from other wise interfering with its continued, smooth and eicient operation.

The invention will be best understood by reference to the following description when taken in connection with the accompanying illustration of one specific embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

l In the drawings: y

Fig. 1 is a sectional elevation showing one form of liquid fuel burner, equipped with a centrifugal atomizing member, embodying one form of the invention;

Fig. 2 is a plan view, on an enlarged scale, showing the atomizer illustrated in Fig. l, the protecting head or cap plate being removed; and

Fig. 3 is a sectional elevation, o n the same scale as Fig. 2, showing the upper part of the atomizing member with the protecting head in position.

Referring to the drawings, I have there shown one form of the invention comprising a centrifugal burner of the upright type similar, except as to the atomizing member, to the burner shown in my co-pending application, Serial No. 247,543, filed January 18, 1928.

As tg many of the features herein disclosed,

how/ever, it may be employed in burners of the horizontal type as well.

The disclosed form of burner comprises a centrifugal, atomizing member located in the combustion chamber of a heater and secured to the upper end of an upright driving shaft or spindle 11. The latter is adapted to be rotated at a relatively high rate of speed, through suitable driving connections 1929. Serial No. 353,824.

and interposed gearing conta-ined within the casing 13, by a horizontal, relatively low speed motor, the casing of which is shown at' 15. The spindle 11 rotates within the bearing sleeve 17, and, except for its upper protruding end, is enclosed within the upright casing 19, the open end of which is covered by the shield 21, leaving only a sufficient clearance for the rotation of t-he shaft within the same, the shield being provided to prevent the entrance of liquid fuel from the atomizer into the casing, or the escape from within the casing of lubricant supplied by the lubricant passage 23.

Air is directed into the combustion chamber space C centrally through an annular air admission passage 25 formed in the lower deflecting plate 27, which latter is provided with walls 29 in the form of a truncated cone. A portion of the air admitted through the passage 25 enters a second annular passage 31 surrounding the atomizer and formed by the upper defiecting plate 33'and passes into the combustion chamber around the exterior of the rotary atomizer. An additional and regulatahle air supplyinay be admitted to the combustion chamber, as described in the aforesaid copending application, around the edges of the upper deflecting plate 33, and a portion of the last named air supply may be allowed to enter the passage 31 over the upper edges of the cone-shaped walls 29, as indicated by the arrows in Fig. 1. Additional air, as hereinafter described, is admitted from the passage 25 to and within the atomizer and is discharged from the latter with the atomized fuel. y

Referring now to the construction of the atomizer, the latter is provided u ith a fuel delivery member orcup, the main body 35 of which is of circular cross section with inclined walls flared slightly outwardly and upwardly. The lower or fuel-receiving end of the cup is formed into a trough-like bottom 37 and is spaced from the shaft 11 and the casing 19 to provide an annular opening '39 through which air may enter and through which liquid fuel is adapted to be delivered by means of the stationary delivery pipe 4l.

An upright portion of the delivery pipe en` ters through the annular opening in the botv'tom ofthe cup between the rim thereof and largement 45 providing a shoulder'- 47 by outwardly inclined delivery llip 49.

'which the cup, as. hereinafter described, is secured to the driving spindle. The open or fuel-delivery end of the cup terminates in an When the atomizeris rotated at aphigh speed, fuel delivered to the 'trough 37 passes in the form of a thin film u'p the side of the preferably of relatively 'thin metal', such, forA cup to the'deliverylip 49, whence it is thrown under centrifugal force into' the `^combustion lchamber. 25

While the cup may be otherwise formed for the reasons hereinafter set forth, it is example, 'as sheet steel. l

To lprotect the open fuel-receiving end of the'icup from the flame and direct heat'of the combustion chamber, a protecting head or cap in the form of a disc-like plate 51 is provided which is fastened'to the reduced end- 58 of the'spindle 11 by the clamping nut 55. The protecting plate 51 is relatively .thin and Ilight and preferably of non-ferrous metal, vivsuch asv brass or aluminum,thereby providing' a high coeicient of heat diffusion. On its under side it i's providedy with an expanded radiating surface in the, form Mof circular fins or "ribs 57. The protecting cap, which provides a cover or closure for substantially all of the open end of the atomizing cup, has its outer beveled edges 59 in close but noncontacting relation to the/ walls of the lip 49, leaving a narrow, peripheral fuel delivery slot 61 and preventing the direct conduction of heat from the wallswof the ,plate tov Athe edges of the cup. i

. When clamped-in position, the' plate 51 f seats against the hubf`63 of a spider-like member, the latter havingfa series (herein six) 1 .i radial arms out, f contactl with the plate but extending to the peripheral walls of the cup, yand carryingl each at its end asmall lug' 65 restinglon'the shoulder47 of the. cup, by l within the cup passes'through the same, also' .helping toscool-the inner wallsof the cup, 1

whichA lugs the spider isfastened to the oup through any suitable means, as by the drivets 67. Each spider arm is providedT near-its;

outer endadjacent the walls of the cup with an enlargement of substantialmass, herein in @the form of a cylindrical Lbossv 68. This adds a certain amount of mass to the periphery of. the cup andaords a means for bringing the cup toa-condition of balance, where its center of gravity will coincide with its geometrical center, by drilling'or otherwise removing the necessary .amount of metal from one or more ofthe bosses as may be required.

To hold the spider, plate and cup in fixed, non-rotative relationship to the shaft 11, the

spider is preferably^ keyed or otherwise secessed 2to form an annular ange,69 through which it seats against the outer edge of a resilient member 71 inthe form of a steel l washer. The latter in1turn is seated against a shoulder` formed by the sleeve 73 pinned or otherwise secured tothe driving spindle 11,-

but has its peripheral edges projecting lateri ally beyond the sleeve. A

.Under the intense heat acquiredfrom the combustion' chamber, the plate '51 and the spider hub 63 tend to expand" in the direction of theaxis of lthe shaft. Under such lconditions, the edges of the .resilientwasher tend to yield and the latter will be forced out of itstrue disc-like formation, returning to its normal shape and position Whenthe head subsequently cools. The plate 71 1therefore presents a resilient abutment vwhich adapts ,itself to such axial expansionY without danger of breaking or rupture ofany of the parts, and permitting their restoration to theinormal conditions and positions when Athe parts are subsequently cooled on vcessation ofthe burner operation.

In the operation of theyburner, the centrifugal atomizing member is driven at 'a high rate of speed, which may, rfor example, be from seven to eight thousand revolutions per minute. The fuel deliveredto `the cup passes up the flared sides'into the cylindrical section 45 about the spider lugs 65 and is thereby dischargedfrom the edge of thean- A nular lip 49,'entering the combustion cham `ber tangentially4 in atomized form and in an approximately horizontal disc-like sheet..

-The cool air which is directed about the exf' I -terior of the cup through` the annular-pas- I sage 31 of the plate '33 provides a la er of airunderlying the sheet of atomize fuel,

and also provides a cooling medium to Iwhich the outer walls of the 'cup a'reexposed, tendl ing to withdraw and dissipate the heatacquiredby thecupland maintain its temperature at a relatively low point. I.

.The air entering the annular openln 39 ail on meeting the radial arms o f. the

rapidly, rotating spider, is agitated, and churnd thereby, causing the transference of of the 'plate and extracting further eat from iin the plate, due to the expanded radiating surface thereof, the air passes through the slot t come excessively hot.

`tion is such that this heat is transmitted di- 61 and is deflected above the sheet of latoinized fuel, providing an overlying layer of air and producing the effect of an atomized sheet of fuel between an upper and a lower sheet or layer of air.

In the operation of an atomizer of this type, it is important that the heat transmitted to the parts of the atomizer which are exposed to the combustion chamber be. rapidly and effectively diffused and that those parts with which liquid fuel comes into contact be maintained at a temperature less than the carbonizing temperature of the fuel. If the cup, for example, becomes overheated and its temperature raised above the c oking point of the fuel the volatile elements will be driven,

oif and the fuel gradually solidified orl carbonized, leaving carbonized accumulations on the inside of the cup which will gradually increase and impair the action of the atomizer and the efficiency of the combustion.

The head or protecting cap, particularly, is exposed to excessive heat, and, in the case of small furnaces, where the burner fiaine strikes the sides and tends to roll back over the top of the burner, the plate tends to belVhere the construcrectly to the side walls of the cup, either through the plate or otherwise, the cup' tends to become overheated and carbonize the fuel.

Vhere the plate is utilized to fasten the cup f to the shaft by contacting with the cup at detached points, the cup is also subject to distortion in shape, particularly where the latter is constructed of sheet metal, due to the fact that the coefficient of the expansion of the head is relatively greater than that of the cup. The effect of such expansion is to produce bulgesl in the Vcup at the points of connection with the plate, thereby concentrating the fuel delivery at certain points instead of providing for a smooth, uniform delivery coming from a truly circular lip or edge.

By preserving a non-contacting relation between the periphery of the protecting plate and the-side walls of the cup and utilizing an independent heat diffusing member, such as thespider, to connect the cup to the shaft, it is possible to support the cup near its fuel delivery enthleaving a retreating cup poi'- tion spaced 'from the shaft and providing the'annular fuel and air inlet opening 39,

, tions maintained relatively cool. This, particularly in conjunction with the maintained currents of air on. the outside and the inside of the cup, keeps the cup relatively cool, preventing the carbonization of the fuel and prei venting any distortions of the cup or alterafrom itstrue circular, cross sectional shape. r

To increase the heat diffusion of the radial arms which form a part of the heat contacting path between the plate and the cup, the latter are preferably provided with upper and lower vertical radiating ribs or vanes 7 5 and 76 and horizontal radiating ribs 77.

Through the described construction of atomizer, the atomizing cup may be made of relatively light sheet metal, which not only reduces the mass of the rotating parts but is susceptible of effective cooling through the Contact with the inner and outer air currents, and the protecting plate may also be made relatively thin and light, also further reducing the mass of the rotating parts, while providing an efficient heat diffusing member.

The capacity of the head and spider to dissipate the 'heat quickly to the air circulating through the cup, and the dissipation of heat from the outside of the cup enables the latter' tobe run below the carbonizing temperature of the fuel'and at the same time raises the temperature of the air entering the combustion chamber to the benefit of effectivecombustion.v

While I have herein shown and ldescribed for the purposes of illustration one specific embodiment of the invention, it is to be understood that extensive changes may be made in the structure of the illustrative embodiment and various changes in the form and relative arrangement may be had, all without departing lfrom the spirit ofthe invention.

Claims: 1. A centrifugal, rotary atomizer for a liquid fuel burner having a driving shaft, a

thin-walled at'omizing cup of circular cross section having upwardly and outwardly llt) for the introduction of fuel therethrough, a

- protecting, disc-like plate covering the open end ofthe cup having its periphery in close but non-contacting relation to the walls of said lip, the inner side of said plate having a ribbed formation, means connecting the delivery end of the cup to the shaft comprising a spider having a hub with radial arms, the ends of which are secured to the peripheral walls of the cup and out of contact with the plate, said plate being clamped against the hub of said spider, and a resilient plate carried by the shaft, against the peripheral edges only of which the hub of said spider is seated to permit of longitudialvexpansion under L the effect of heat. 2. A centrifugal, rotary atomizer for a liquid fuel burner having a rotary shaft, an 5 atomizing cup secured to said shaft, a pro tectinghead for said cup exposed to the heat' of the combustion chamber and also mounted on said shaft, anda resilient abutment carried by the shaft and opposing axial expansion 'of said head when the latter is heated.

3. A centrifugal, rotary atomizer for a liquid fuel burner having a rotary shaft, an atomizing cup, a spider having a hub mounted on said shaft and connecting the cup thereto, and a resilient plate carried by the shaft against the peripheral edges only of`vvhieh the hub of said spider is seated to' permit the tlxial expansion thereof under the effect of.

eat. i 4. A centrifugal, rotary atomizer for a liqliid fuel burner having 'a rotary shaft, 1an

a oniizing cup secured to said shaft, a heat protecting head for the delivery end of theatomizing cup also mounted on said shaft,- and ,yieldalole means carried by the shaft adapted to permit the axial expansion of said heat protecting head. y In testimony whereof, I have signed my name to this specification.Lr

. 30. EZEKIEL F. WHITE. 

